 /*******************************************************************************
  * Copyright (c) 2000, 2005 IBM Corporation and others.
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License v1.0
  * which accompanies this distribution, and is available at
  * http://www.eclipse.org/legal/epl-v10.html
  *
  * Contributors:
  * IBM Corporation - initial API and implementation
  *******************************************************************************/
 package org.eclipse.ui.internal.texteditor;

 import org.eclipse.jface.action.Action;
 import org.eclipse.jface.action.IAction;
 import org.eclipse.jface.viewers.ISelection;
 import org.eclipse.jface.viewers.ISelectionProvider;

 import org.eclipse.jface.text.Position;
 import org.eclipse.jface.text.TextSelection;

 import org.eclipse.ui.IEditorPart;
 import org.eclipse.ui.IEditorSite;
 import org.eclipse.ui.IWorkbenchPage;
 import org.eclipse.ui.IWorkbenchWindow;
 import org.eclipse.ui.IWorkbenchWindowActionDelegate;
 import org.eclipse.ui.PartInitException;
 import org.eclipse.ui.PlatformUI;
 import org.eclipse.ui.texteditor.IAbstractTextEditorHelpContextIds;
 import org.eclipse.ui.texteditor.ITextEditor;
 import org.eclipse.ui.texteditor.ITextEditorActionDefinitionIds;

 /**
  * Goes to last edit position.
  *
  * @see org.eclipse.ui.internal.texteditor.EditPosition
  * @since 2.1
  */
 public class GotoLastEditPositionAction extends Action implements IWorkbenchWindowActionDelegate {

     /** The worbench window */
     private IWorkbenchWindow fWindow;
     /** The action */
     private IAction fAction;

     /**
      * Creates a goto last edit action.
      */
     public GotoLastEditPositionAction() {
         PlatformUI.getWorkbench().getHelpSystem().setHelp(this, IAbstractTextEditorHelpContextIds.GOTO_LAST_EDIT_POSITION_ACTION);
         setId(ITextEditorActionDefinitionIds.GOTO_LAST_EDIT_POSITION);
         setActionDefinitionId(ITextEditorActionDefinitionIds.GOTO_LAST_EDIT_POSITION);
         setEnabled(false);
     }

     /*
      * @see IWorkbenchWindowActionDelegate#init(org.eclipse.ui.IWorkbenchWindow)
      */
     public void init(IWorkbenchWindow window) {
         fWindow= window;
     }

     /*
      * @see org.eclipse.ui.IActionDelegate#run(org.eclipse.jface.action.IAction)
      */
     public void run(IAction action) {
         run();
     }

     /*
      * @see IAction#run()
      */
     public void run() {
         EditPosition editPosition= TextEditorPlugin.getDefault().getLastEditPosition();
         if (editPosition == null)
             return;

         final Position pos= editPosition.getPosition();
         if (pos == null || pos.isDeleted)
             return;

         IWorkbenchWindow window= getWindow();
         if (window == null)
             return;

         IWorkbenchPage page= window.getActivePage();

         IEditorPart editor;
         try {
             editor= page.openEditor(editPosition.getEditorInput(), editPosition.getEditorId());
         } catch (PartInitException ex) {
             return;
         }

         // Optimization - could also use else branch
 if (editor instanceof ITextEditor) {
             ITextEditor textEditor= (ITextEditor)editor;
             textEditor.selectAndReveal(pos.offset, pos.length);
             return;
         }

         /*
          * Workaround: send out a text selection
          * XXX: Needs to be improved, see https://bugs.eclipse.org/bugs/show_bug.cgi?id=32214
          */
         if (editor != null) {
             IEditorSite site= editor.getEditorSite();
             if (site == null)
                 return;

             ISelectionProvider provider= editor.getEditorSite().getSelectionProvider();
             if (provider == null)
                 return;

             provider.setSelection(new TextSelection(pos.offset, pos.length));
         }
     }

     /*
      * @see org.eclipse.ui.IActionDelegate#selectionChanged(org.eclipse.jface.action.IAction, org.eclipse.jface.viewers.ISelection)
      */
     public void selectionChanged(IAction action, ISelection selection) {
         boolean enabled= TextEditorPlugin.getDefault().getLastEditPosition() != null;
         setEnabled(enabled);
         action.setEnabled(enabled);

         // This is no longer needed once the action is enabled.
 if (!enabled) {
              // adding the same action twice has no effect.
 TextEditorPlugin.getDefault().addLastEditPositionDependentAction(action);
             // this is always the same action for this instance
 fAction= action;
         }
     }

     /**
      * Returns the workbench window.
      *
      * @return the workbench window
      */
     private IWorkbenchWindow getWindow() {
         if (fWindow == null)
             fWindow= PlatformUI.getWorkbench().getActiveWorkbenchWindow();
         return fWindow;
     }

     /*
      * @see IWorkbenchWindowActionDelegate#dispose()
      */
     public void dispose() {
         fWindow= null;
         TextEditorPlugin.getDefault().removeLastEditPositionDependentAction(fAction);
     }
 }

